Carboxylic acid - n - methyl-piperazides and their utilization as anthelmintics



United States Patent Int. c1. A61k 27/00; C07d 51/70 US. Cl. 424-250 2 'Claims ABSTRACT OF THE DISCLOSURE Anthelmintic compositions for oral or parenteral administration comprising a carrier and a piperazrde of the formula wherein R is alkyl, cycloalkyl, or cycloalkyl having a double bond, an endomethylene group, an oxygen or sulfur atom, an imino group, or a methyl group. Method of combatting Helminths therewith.

This application is a division of Ser. No. 521,445, filed Jan. 18, 1966, now Patent No. 3,373,163.

The present invention relates to carboxyllc acld-N- methyl-piperazides corresponding to the general formula and to their physiologically tolerable salts as well as to a process for preparing them.

In the above-mentioned formula R represents an alrphatic radical containing 3 to 6 carbon atoms which may be branched, or a cycloaliphatic radical containing to 7 carbon atoms which, in addition, may contain a double linkage, an endomethylene group, an oxygen or a sulfur atom or the imino group or which may be substituted by a methyl group.

The process is materialized by (a) Reacting a reactive derivative of a carboxylic acid of the Formula II RCOOH (II) with N-methyl-piperazine, or

(b) Reacting a carboxylic acld-piperazide of the Formula III R-GO-N/ NH (III) with a methylating agent or (c) Hydrogenating a carboxylic acid N methylpiperazide of the Formula IV N-OH; in which R represents a radical containing multiple linkages which is converted into the radical R by hydrogenation, or

(d) Reacting a carboxylic acid amide of the Formula V 3,484,524 Patented Dec. 16, 1969 with inorganic esters of N-methyl-bis-(p-hydroxy-ethyD- amine and, if desired, by converting the products obtained into the corresponding salts by means of physiologically tolerable acids.

(a) As reactive derivatives of carboxylic acids which are used as starting substances for the process according to (a), there are particularly suitable the acid chlorides, but other reactive derivaties such, for example, as carboxylic acid fluorides, carboxylic acid bromides, carboxylic acid esters, carboxylic acid anhydrides, carboxylic acid azides, mixed anhydrides with carbonic acid semiesters, carboxylic acid imidazolides and the like may likewise be used. They are derived, for instance, from butyric acid, isobutyric acid, valeric acid and its isomers, caproic acid and its isomers, cyclopentane-carboxylic acid, cyclohexane-carboxylic acid, or cyclohexene-carboxylic acid and their methyl-substituted homologs, endomethylenecyclohexane-carboxylic acid or tetrahydropyrane carboxylic acid.

When reacting acid chlorides with N-methyl-piperazine, the presence of a solvent is prefeired. As solvents there are used, for instance, aliphatic or aromatic hydrocarbons such as benzine, benzene or toluene, ethers such as diethyl ether, diisopropyl ether, anisol, tetrahydrofurane or dioxane, esters such as ethylor butyl-acetate, ketones such as acetone or methyl-ethylketone, amides such as dimethyl-formamide or nitriles such as acetonitrile. The reaction can be carried out at a low temperature as well as at an elevated temperature, for instance, at the boiling temperature of the solvent. It is of advantage to start the reaction at room temperature and to complete it by heating, for instance to the boiling point of the solvent.

If the reactants are used in equimolar amounts, the hydrochlorides of the piperazides are formed, which according to the solvent selected, can largely be separated in crystalline form and isolated by filtration. It is likewise possible to remove the hydrogen halide liberated 1n the course of the reaction by means of acid-binding agents for instance inorganic bases such as sodium carbpnate or sodium hydroxide or tertiary amines such as, for example, triethylamine, dimethylaniline or pyridine, or likewise an excess amount of piperazine. When operating in this way, the free carboxylic acid piperazides are formed, which in most cases remain in dissolved state and which can be recovered in the usual manner, for instance by evaporation of the solution. If necessary, greasy by-products are removed by filtration. The carboxylic acid-N-methyl-piperazides are purified by distillation under reduced pressure.

The piperazine can be used for the reaction also in the form of a salt. In this case, the acid-binding agent is used in excess so that the free base is formed from the piperazine salt. The free carboxylic acid piperazides thus obtained can be isolated as described above. The other reactive carboxylic acid derivatives mentioned above can be reacted with N-methylpiperazine in an analogous manner.

If, according to the invention, mixed anhydrides with carbonic acid semi-esters are used as starting materials, it is of advantage to react corresponding carboxylic acids in an appropriate solvent, for example, dioxane or tetrahydrofurane, at temperatures between -20 and +30 C., preferably at 10 C., in the presence of a tertiary base, for example triethylamine, with a carbonic acid semiester, for instance, chloroformic acid-tert.-butylester and to have the mixed anhydride thus formed reacted with N-methyl-piperazine. The latter reaction stage can be carried out at temperatures between 20 and +50 C. It is suitable to start at a temperature below 0 C. to complete the reaction at room temperature.

(b) The products can likewise be obtained by methylation of a carboxylic acid piperazide of the formula It results therefrom that the products obtained according to the present invention are distinctly superior to N,N-diethyl-4-methyl-l-piperazine carboxylic amide. Moreover, RCON NH the toxicity of the products, of the invention is inferior 5 to that shown by N,N-diethyl-4-methyl-l-piperazine-car- AS methylatihg agents the methyl esters of Strong thorboxamide. The toxicity was determined by treating garlic acids, Such as yl iodide, methyl bromide, mice each orally or 10 rats each subcutaneously with difmethyl Sulfate and p-tehlehe-sulfollie acid methyl eSter ferently high doses and by ascertaining the animal death are appropriate. rate.

The methylation is carried out in neutral solvents such 10 as alcohol, dioxane or nitrobenzene. It is, however, likeg g fg g fi gg gfg fi wise possible to operate in alkaline solution, by adding the rate in percent rate impe -cent methylating agent to an alkaline solution of the carfggighf ggf f gghi fg i boxylic acid piperazide. N -met,h ylazine-carbpx- (c) A further process for preparing carboxylic acid-N- 1 Plpemlde amlde methyl-piperazide consists in the hydrogenation of com- Dose subcutaneously administered: pounds of the Formula IV which in the carboxylic acid 8 $8 radical contain one or several multiple linkages. The carsxssoIIII 0 boxylic acid part may be derived, for instance, from unggggg Z; 5 X 400 saturated aliphatic carboxylic acids such, for instance, as crotonic acid, butene-carboxylic acid, isopentene-carboyl- Mice animal ic acid, butadiene-carboxylic acid, isohexene-carboxylic percent tetradeath rate in acid, isohexadiene-carboxylic acid or from cyclic cargggggggg ggffgfi g h boxylic acids containing double linkages, for instance acid-N-methyll-piperazinebenzoic acid, cyclohexene-carboxylic acid and cyclohexaplpemzlde carboxamlde diene-carboxylic acid. Triple linkages may likewise be Dose orally administered:

1 1500 0 100 present in the carboxylic acid part. 20 100 The hydrogenation is performed in known manner by 20 means of Adams catalysts, for instance, platinum or pal- Doses mama/kg M1500 1x580 ladium or nickel catalysts, in appropriate solvents such 5X650n1g. as water, alcohols, acetic ester, glacial acetic acid or mix- The products Obtained according the process of h tures of said solvents, if desired with addition of mineral present invention can be used as such i the fo f acid at a Preferably elevated temPeYathYe under their salts with non-toxic acids, if desired in admixture evated Pressure in an atmosphere of hydfogehof pharmaceutically tolerable inert auxiliary and carrier Furthermore, it is Possible to use for the Process substances, orally or parenterally, preferably orally. They according to the invention inorganic esters of N-methyl' are preferably used in the form of tablets or suspendable (5 Y Y- Y amine, for instance, N methyl (5' powders which when given to animals can be mixed yn- Y '(fiy OF with the food. A powder suspendable in water may con- N'methyl(fi'shlfohehydroxy'ethyl)amine and to react tain a carrier and auxiliary such as finely divided silicic these with carbonic acid amides of the Formula The 40 acid or a dispersing agent such as coconut lorol sulfonate reaction is Carried out in HOB-Polar Solvents, Preferably in addition to the products of the invention. For the toluene, and Suitably at an elevated temperature, for preparation of tablets the usual substances known as bases Stance the boiling temperature of the Solvent, in the P for tablets, such for instance as maize starch, lactose, ence of very strong alkaline agents such as sodium-amide peetihs, above l ultra amylepeetin i Potassium-amide, sodiuhl'hydride 0f -P Y glycolate), talc and the like are used. In certain thera- The eafhoXyhe acid Pipefazides Obtained according to peutical cases other anthelmintics and/or antibiotics may the invention are monoacid bases and form salts with inb i d The l i preparations are d d organic and organic acids which in most cases are obcording to h usual methods, tained in crystalline form- AS acids Suitable for the forma The following examples serve to illustrate the invention tion of salts there are named, for instance, hydrochloric b they are not intended to i i i thereto; acid, acetic acid, citric acid and maleic acid. The salts are more or less readily soluble in Water. EXAMPLE 1 The products obtained according to the process of the To a mixture consisting of 20 grams of N-methyliperpresent invention show a strong anthelmintic activity, W azine, 20 grams of triethylamine, and 400 ml. of ethyl above all on filariae. Filiariasis is widely spread, particacetate, a solution of 21.4 grams of butyric acid chloride ularly in tropical countries. Compared with the known in milliliters of acetic ester is added dropwise with N,N-diethyl-4-methyl-l-piperazine-carboxamide the prodstirring. Upon termination of the dropping in, stirring is ucts obtained according to the invention show an incontinued for a further 2 hours, the triethylamine-hydrocreased etficiency against the filaria Litosomoides carinii chloride which separates is filtered off with suction and as shown by the following comparison: the solvent is evaporated under reduced pressure. 200 Cotton rats infected with Litosomoides carinz'i were milliliters of absolute ether are added to the residue, the treated orally or subcutaneously on five successive days brownish greasy substance which is hereby formed in a with varying doses of the compound to be examined. small amount is removed by filtration with charcoal, the After a certain number of days following the start of the e ether is eavoparted and the residue is distilled. 28 grams treatment, the decrease in percent of the micro filaria 69 of butyric acid-(N-methyl-piperazide) are obtained. was determined in comparison with the initial value and In order to convert the compound into the maleinate, the average value was ascertained from the values found. it is added to a solution of 19 grams of maleic acid in 200 Decrease of micro filariae in percent days after start of treatment Average Preparatlon Dose 6 12 18 24 value (lyelohexanetcarboxylic acid N-methyl-piperazide. 5 X 30 mg./kg. sucutaneously-.. 96. 8 93.9 74. 6 86. 5 88.2 N,N-diethyl-et-methyl-l-piperazine-carboxylic amide do 75.2 67.6 63.1 74.7

milliliters of ethyl acetate, whereby the maleinate separates. Yield 42 grams showing a melting point of 94 C. (from ethyl-acetate).

In the same manner the following N-methyl-piperazides, which may analogously be converted into their the crude product is taken up in 300 milliliters of chloroform, the undissolved N-methyl-piperazine-hydrochloride is filtered oil and the filtrate is concentrated by evaporation. Upon addition of ethyl-acetate the pure butyric acid- (N-methyl-piperazide)-hydrochloride separates, which is maleinates by reaction with molar amounts of maleic 5 recrystallized from a mixture of butanol and ethyl-acetate. acid, are obtained from molar quantities of the corre- After drying on the steam bath: Yield 14 grams of a sponding acid-chloride: melting point of 157-159 C.

Boiling point Melting point Formula of the of the base, of the malein- Chloride N-methylpiperazide mm. ate, degrees CH CH 011-0001 CH-CO-N N-CHz 100-102/4 137 v Ofi3 CH3 c OH (OH COCl CHr-(OHzh-CO-N N-CH3 120-l23/3. 104

CH CH d CH-OH -COCI CHCH2C0N /N-CH 117-119/4 11s CH3 CH3 e CH -(CHzh-COCI CHg-(CHflr-CO-N N-OH; 133-134/4 115 CH -C CH3CH2 f 011-0 0 O1 CH-C ON N-CH 116118/4. 145

g OH;C a CHg-CH:

CH CH CHOHzOH-C 0 01 CH-CH -OH-C 0- N N-CH 120-122/4 84 CH3 CH3 033 H3 3 3 h /CH-CIC 0 Cl /CH(IJC ON )I-OH; l21123/4 133 CH3 CH3 CH3 CH3 1 00o1 OON N-OH 138l40/4 141 3 Q0001 CON N-CHa 146l3 s k 0 '00o1 K -C0N N-CH 176178/7 149 CH CH 1 o o 01 CON NCH 153/4 134 o0c1 0 ON N-CH 156159/5 177 Instead of the maleinates, the citrates can be prepared We claim:

EXAMPLE 2 To a solution of grams of N-methylpiperazine in 200 milliliters of ethyl-acetate a solution of 21.4 grams of butyric acid chloride in milliliters of ethyl-acetate is added while stirring. The temperature spontaneously rises to 58 C. and an oil precipitates which solidifies after some time. After cooling, it is filtered oil with suction and washed out with ethyl-acetate. In order to remove the admixed N-methyl-piperazine-hydrochloride,

1. A composition for vcombatting filariae consisting essentially of a physiologically tolerable carrier suitable for oral or parenteral administration in admixture with an 'anthelmintically effective amount of a member selected from the group consisting of a carboxylic acid-N-methylpiperazide and its physiologically tolerable salts, Said piperazide having the formula RC ON/ N-OHa wherein R is a member selected from the group consisting of:

(A) saturated and olefinically mono-unsaturated cycloaliphatic hydrocarbons having 5-7 carbon atoms;

(B) such hydrocarbons having a monomethyl substituent thereon; (C) bicyclo [2.2.1]hept-5-ene-2-yl; and

(D) 4-tetrahydro pyranyl.

7 8 2. In the method of combatting filariae, the step of FOREIGN PATENTS orally or aparenterally administering to animals, an ant- 218 021 11/1961 Austria helmintically effective amount of a composition as defined in claim ALBERT T. MEYERS, Primary Examiner References Cited 5 UNITED STATES PATENTS V. O. TURNER, Assistant Examlner 3,373,163 3/1968 Loewe et a1. 

